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3. Available-for-Sale Investments (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Millions, unless otherwise specified | Mar. 31, 2015 | Dec. 31, 2014
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Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Amortized Cost | $ 334.6 us-gaap_AvailableForSaleSecuritiesAmortizedCost |  | $ 334.9 us-gaap_AvailableForSaleSecuritiesAmortizedCost |
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax | 262.3 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax |  | 251.6 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax |
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax | 0.4 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax |  | 0.6 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax |
Estimated Fair Value | 596.5 us-gaap_AvailableForSaleSecurities | [1] | 585.9 us-gaap_AvailableForSaleSecurities | [1]
Corporate Debt Securities [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Estimated Fair Value | 138.7 us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | [1] | 139.9 us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | [1]
Foreign Brokered Certificates of Deposit [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Estimated Fair Value | 5.2 us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CertificatesOfDepositMember | [1] | 5.2 us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CertificatesOfDepositMember | [1]
Municipal obligations [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Estimated Fair Value | 6.5 us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MunicipalBondsMember | [1] | 6.5 us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MunicipalBondsMember | [1]
Asset-backed Securities [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Estimated Fair Value | 47.1 us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember | [1] | 48.4 us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember | [1]
Marketable Equity Securities [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Estimated Fair Value | 345.2 us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember | [1] | 334.4 us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember | [1]
US Government Sponsored Agencies [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Estimated Fair Value | 50.0 us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasuryAndGovernmentMember | [1] | 47.5 us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasuryAndGovernmentMember | [1]
Foreign Government Obligations [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Estimated Fair Value | 3.8 us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ForeignGovernmentDebtSecuritiesMember | [1] | 4.0 us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ForeignGovernmentDebtSecuritiesMember | [1]
Other Long-term Investments [Member] | Asset-backed Securities [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Amortized Cost | 0.3 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | 0.4 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |
Estimated Fair Value | 0.3 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | 0.4 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |
Other Long-term Investments [Member] | Marketable Equity Securities [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Amortized Cost | 54.5 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember |  | 54.5 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember |
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax | 256.7 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember |  | 246.6 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember |
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember |  | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember |
Estimated Fair Value | 311.2 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember |  | 301.1 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember |
Other Long-term Investments [Member] | Available-for-sale Securities [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Amortized Cost | 54.8 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AvailableforsaleSecuritiesMember |  | 54.9 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AvailableforsaleSecuritiesMember |
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax | 256.7 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AvailableforsaleSecuritiesMember |  | 246.6 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AvailableforsaleSecuritiesMember |
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AvailableforsaleSecuritiesMember |  | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AvailableforsaleSecuritiesMember |
Estimated Fair Value | 311.5 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AvailableforsaleSecuritiesMember |  | 301.5 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_OtherLongTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AvailableforsaleSecuritiesMember |
Short-term Investments [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Estimated Fair Value | 285.0 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |  | 284.4 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember |
Short-term Investments [Member] | Corporate Debt Securities [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Amortized Cost | 138.4 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |  | 139.7 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax | 0.4 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |  | 0.4 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax | 0.1 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |  | 0.2 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |
Estimated Fair Value | 138.7 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |  | 139.9 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember |
Short-term Investments [Member] | Foreign Brokered Certificates of Deposit [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Amortized Cost | 5.2 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CertificatesOfDepositMember |  | 5.2 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CertificatesOfDepositMember |
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CertificatesOfDepositMember |  | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CertificatesOfDepositMember |
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CertificatesOfDepositMember |  | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CertificatesOfDepositMember |
Estimated Fair Value | 5.2 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CertificatesOfDepositMember |  | 5.2 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CertificatesOfDepositMember |
Short-term Investments [Member] | Municipal obligations [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Amortized Cost | 6.5 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MunicipalBondsMember |  | 6.5 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MunicipalBondsMember |
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MunicipalBondsMember |  | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MunicipalBondsMember |
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MunicipalBondsMember |  | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MunicipalBondsMember |
Estimated Fair Value | 6.5 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MunicipalBondsMember |  | 6.5 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MunicipalBondsMember |
Short-term Investments [Member] | Asset-backed Securities [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Amortized Cost | 46.9 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | 48.2 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax | 0.1 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | 0.2 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |
Estimated Fair Value | 46.8 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |  | 48.0 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember |
Short-term Investments [Member] | Marketable Equity Securities [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Amortized Cost | 29.3 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember |  | 29.0 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember |
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax | 4.9 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember |  | 4.5 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember |
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax | 0.2 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember |  | 0.2 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember |
Estimated Fair Value | 34.0 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember |  | 33.3 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember |
Short-term Investments [Member] | Available-for-sale Securities [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Amortized Cost | 279.8 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AvailableforsaleSecuritiesMember |  | 280.0 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AvailableforsaleSecuritiesMember |
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax | 5.6 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AvailableforsaleSecuritiesMember |  | 5.0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AvailableforsaleSecuritiesMember |
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax | 0.4 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AvailableforsaleSecuritiesMember |  | 0.6 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AvailableforsaleSecuritiesMember |
Estimated Fair Value | 285.0 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AvailableforsaleSecuritiesMember |  | 284.4 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AvailableforsaleSecuritiesMember |
Short-term Investments [Member] | US Government Sponsored Agencies [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Amortized Cost | 49.7 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasuryAndGovernmentMember |  | 47.4 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasuryAndGovernmentMember |
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax | 0.3 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasuryAndGovernmentMember |  | 0.1 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasuryAndGovernmentMember |
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasuryAndGovernmentMember |  | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasuryAndGovernmentMember |
Estimated Fair Value | 50.0 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasuryAndGovernmentMember |  | 47.5 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasuryAndGovernmentMember |
Short-term Investments [Member] | Foreign Government Obligations [Member] |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |
Amortized Cost | 3.8 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ForeignGovernmentDebtSecuritiesMember |  | 4.0 us-gaap_AvailableForSaleSecuritiesAmortizedCost / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ForeignGovernmentDebtSecuritiesMember |
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ForeignGovernmentDebtSecuritiesMember |  | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ForeignGovernmentDebtSecuritiesMember |
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ForeignGovernmentDebtSecuritiesMember |  | 0 us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ForeignGovernmentDebtSecuritiesMember |
Estimated Fair Value | $ 3.8 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ForeignGovernmentDebtSecuritiesMember |  | $ 4.0 us-gaap_AvailableForSaleSecurities / us-gaap_BalanceSheetLocationAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsRecurringMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ForeignGovernmentDebtSecuritiesMember |
[1] | Available-for-sale investments are included in the following accounts in the Condensed Consolidated Balance Sheets (in millions): March 31, 2015 December 31, 2014Short-term investments$285.0 $284.4Other investments311.5 301.5Total$596.5 $585.9

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